Tilting chair back



DCL 7, 1952 J. s. BURDixcK 2,612,939

TILTING CHAIR BACK Filed May 15, 195o I?? vena/f' Oct. 7, 1952 J. S.BURDICK TILTING CHAIR' BACK 2 SHEETS-SHEET 2' Filed May 15, 1950Patented Oct. 7, 1952 y :TII'ITING CHAIRQBACK Jahn' Smetana-NorthMuskgbh;'M1h.,xass`ignnr to The -Shawlvtfalkex' Company, 'Muskegom`Mich., a'corporation' of Michigan Applicationz yMay-.115, 1950,'SerittIxNo.y 162,025

l LThis `inventionrelates :,.to improvements in iopclaims. (cuss- 4156ihowever, it will bevconsidered thattthebackr thebacks of the greaternumber of its` or:cupa-nts` d regardless of its shape, form ordimensions.

N...The,principal object .ofthe invention isto pro,

vide ar simple form. `of tilting back unitrnounted Within theystationary chair back frame lso Qasto automatically tilt `or adjustitself. to `the proper angular position tontthe occupantsback. d d

Atturther object is togprovide'a `tilting .back

unit l which is ,capableA of `limited vertical adjust-.

ment ...relative to the lsiderails l of .a1stationary.

Y backV support,V to racconirnodate :persons of fdifferf ent,sizes,with`the `object. of making it possible iortheplaceinent of the convexity.'ofthefback unit .in `the correct ,tilt and vertical position, `fortheiproperssupport of therlumbar 4:region of lthe occupants back.

@While the lnwentiodis particularly adapted f foruse .with oillcechairs,itcan be.` applied Vto any .design of ,chair .having `a stationary backtraine` and .wherein the l tilting back `and its surroundingframe may beof simpleslattedfframe j construction `or 'of` luxuriously upholstered'con-` struction, y .1- Y l.. -A TheY invention. may. best, beunderstoodby lref-` erence to the accompanying d'rawings,.inwhich:`

Figure `14 is `a `View in side.d elevation .of la. chair made,inaccordance with4 my invention;

Figure 1; v

Figure ',3is anu enlarged :detailed `section `taken online ,3 3 ofFigure f2; s 1

Figure 1-4 is enlarged detailed section taken vliandside oftheftiltingback unitas shownlin Figureibut drawnto a largerscalefthantthe latter gure; d d d d l Figure 6 is a I partial .viewsimilar: to .Figure 4,

Withparts in diierentjpositions Y "Referring now `to the `embodiment i,of` .my inv vention` illustrated in ,the drawings, .the same i is shownas-appliedato an ordinary straightfbackl chair; including .afseat I 0,front llegs t I I, I I reary dicated generally 'at l5;

In the formfshown her-emana ,back framemcludes .a top ran Is and uprightl side rails i I 'I which extend downwardly to the `seat I 0. As shownherein, the

sidegrailsvll farellcontinuous with therear legs;

.A tilting bak'unit, indicated generally at la, is arranged to t `Withinthe open `area formed:

bythe top Irail I6 Vand-side rails .Iloftheback frame I5. Said tiltingunit consistsof eaksecond frame having top andbottom frame members I8`and 20 4and side frame "members 2I.2I. vThe area `between said framemembersxis filled bya suitable supporting rweb, indicated l, `generally@at 22,- herein formed byfaplurality ,of uprightt slats 23 23. It willbe understood,ihowevei-that the supportingweb 22 of themtilting` unitmay 4beof various forms; as ,for instanceiitfmayiconsist of a vsolidbacking. .or upholsteredrmaterial. `In any'case, the frontA of thesupporting web .(22. of the` tilting unit ispreferablyformedlslightlyconvexiin yverticalsectionifromftop tobottomtand slightly i concave in `,horizontal section,l so fas( topresent an approximateform-iitting surfacezior` 'the `backof-theaverage. user- Y v i 'The tilting backpunit s I 8 is arranged?iorftilting as rawhole f about sa'transverse axis-intermediateits'topwand bottom framemembers I gaand 20,'` said 24,124. :each mountedony one end of; an adjusting arm adjacentv theiinner sides of` thesidelrails ITtof-.Lthe lopen bacial frame i I 5. The oppositeeend of @theytwo adjustingfarxns25, 25,are mounted on bolts 26,26 whicnjlhewe4threaded engagement in :trunnions 21, 2.1 :suitably "fixed to ithevinnenfacesfof the uprightsiderails IT. `'I'heendsy of the. adjusting arms"Aditiwengage :the proximate faces of `the :'trunnons 21 withfsuitable4friction lock 'devices 1 for holding each'arxn 15 randttrun.- nion 2lAagainst'*relative movement inivarious' adl- .iusted positions. 'In theform 'shown herein.. said friction lock devices 4consistoffserrated,'finl-` tertting teeth'28 Vand' 29 on'the `arms 25"a'ndtrun'nion 21, respectively. Sai'dlteeth holdfeach vadjusting arm; infamydesired angular relation to the adjacent trunnion 2l when tlieboltZIi`is tightened. l l d In the` form shown herein, a pair fof jL`-shape`dbrackets 3U, 30 connect the Vouter ends of .the pivot pins.24,.24.tothe, rearfaee ofthesiciejfratxie` membersll, 2| ofthetilting'back-unitI"B.,Fricf tionwashers 3I, v3| may beinterposedlhetween the adjacent. `faces of the L-shape'd brackets 13Dandthe adjusting yarm v2li, .andspring .v'vasherfs'` 32, ,32- may be.interposed between the outer heads l the l.-shaped 1 .brackets 24a of`pivot pins `2.4- and 30 (see Fgurez), i

EAs-'will be seen in` Figures 1 andzfthe 21, 21 and the adjusting arms25, 25 connected thereto are preferably disposed nearer the bottom thanthe top of the tilting unit I8, so that a relatively free tiltingmovement of the unit I8 is permitted about the axis defined by the pivotpins 24, 24approximately atthe level of., the small of the backoftheavera'ge'occupant when seated in the chair in upright position. The

arms 25, 25, however, can be adjusted to various angles with respect tothe trunnions 21, 21 soA as to shift the relatively free pivotalmovement of the tilting unit into a slightlyhigher.orlower position, asdesired, to accommodate theunitf v to persons of different lengths oftorso.' L It will be observed further that the adjustment accommodatedto the back of the occupant as f the arms 25, 25 relative to vthetrunnions 21,

21 will cause a rearward movement of the axis of when the arms 25 areswung either upwardly or downwardly with respect toa forward, generallyhorizontal position of saidf arms. This vtype of adjustment affordsA astillgreater latitude of adjusting movement of the back unit withrespect to the chair as a whole, tosatisfy the preference ofthe'per'so'n who usually occupies the chair.

` The trunnions 21, 21are provided with inward-'- ly. 'extending stopmembers 21a, 21d in position to: Vlimitthe angular and verticaladjustment of fthe lposition' ofA the -latter may be changed from ltimevto time. 15.

l Moreover, the axis of tilting movement of the back unit I8`ca`n beraised or lowered within cer- A tainlimits by readjusting the arms 25,25 into relatively free tilting movement of the back unitv the arms 25with respect to'sai'd trunnions so that the axis of relatively f reepivoting movement of the tilting yback unit defined by pivot pins`V 24is' maintained in advance of the axis about which the arms 25`r'areadjusted relative to the trunnions 21. Accordingly, `in all permissiblepositions'bf vertical'adjustment of the tilting back unit 18, theupright side frame members 2| of said v'tiltingback' unit are normallymaintained in position well forwardly of and along the front aGesCf-theproximatestationary side rails I1 of the chairadjacent the'trunnions 21,as indicated in Figures l, 3 and 4'.

Rearward movement ofthe top 'of the 'tilting unit I8 -is limited in allpositions of vertical adjustment of arm 25by engagement with avertically disposed stop member33, herein consisting' of a' Slat-34connected and extended between the rear lface of the upper rail I6' ofthe stationary back frame and a horizontal r'ail 35 connecting`tl'ieside rails I1,` I1 of the stationary chair frame,

frame includes a top yrail I6, the upper end of the vertical back stopmember is preferably arranged sothat the front face of theupper framemeinber I9 of the tilting unit cannot swing rearwardly beyond the frontface of said top rail I6, re-

gardless of the vertical position of adjustment of the tilting unit as awhole.

The use and operation of the device above described is as follows:

The tilting back unit Iuis free to accon'imodateV itself automatically.to the backs of occupants of i varying builds by tilting on the axisdefined by the pivot pins 24, 24, merely by the pressure nor-v mallyexerted against the chair back,` in whatever, seating position theoccupant happens to assume in the chair. Since the back unit extendsabove and below its intermediate tilting axis with its majorportion'above said axis, it will be tilted different angular positionswhere they will Ibe maintained by tightening the bolts 26. In allpositionsl of :such vertical adjustment, the side frame members `2l ofthe tilting unit will be( disposed well forwardly Aof the 'adjacent siderails I1 o f the stationary back frame sov that the o ccupants back doesnot come intocontact' with the stationary side rails I1jat any time.,Furthermore, the front' face ofthe topframe member I9'of the tiltingunit cannot swingrearwardly'of the'front face of the adjacent topfrailI6-of the'stationary back frame. This arrangement eliminates anypossibility of discomfort to the occupant during relatively freejtilting movements of the back unit I8, which otherwise might cause aportion of the occupants `back or head to bel brought suddenly intocontact withftlienside y top rails of the stationary `back'frax'ne.

. When the axis of tilting'movement 'of the y'bac'lc' unit is properlyadjustedverticallyjso'as to bel substantially atthe' level of thesmallof `the back of the user, the 'unit can bev tilted automaticallyand relatively freely in either direction against slight frictionalresistance, to' readjust itself to the most comfortable positionfforvvtl'ieoccupant'.'A The improved back structure is extremely simple inform and, in particular; retains the gen-l eral appearance of a'conventional chair, since the trunnions and vertical adjusting arms aredisposedbetween the upright side` railsOf the back frame, so las to bepractically invisible from front andsides of the chair.' f i Although Ihavev shown and' described [certain embodiments of my invention, it will4be understood that I'do not wish to be limited to theexact constructionshown and de scribed, but thatvvarious changes and modifications maybemade withoutdepartment from the spiritand scope of the invention asdenedin the' appended claimsl'V wenn: i .p j r i l. In a chair having aseat vand a substantially open back frame dened by'continuous top andside; rails, avv backunit pivotally mountedin said` open back frame fortilting movement on a transverse axis intermediate the top and bottom'ofsaid unit and approximately at the level 0f the small of the back of theaverage adult occupant, said back unit substantially filling said openback frame'to form thebackrestvof said-chair, the major portion 'of saidunit being disposed above said axis to permit 'reverselyv tiltableadjustment bypressure of the .occupants back above or below said axis,`the pivotal supportforsaid backunit comprising a pair of trunnions fixedto the'side' rails of said open back frame `and between which trunnionsthe back unit has limited relatively free tilting adjustment. saidtrunnions including arms", each having one of their ends adjustable'onhorizontal axes to varying fixedV angular positions relative to saidback frame, and the other end of each of said arms having the adjacentside of said back unit pivotally mounted thereon for tilting movementrelative to said arms, and for vertical bodily adjustment relative tosaid back frame.

2. A chair structure in accordance with claim l,

'wherein stop means are provided on the back frame for limiting thetilting movement of said back unit with the side margins of said unitdisposed in the front of the side rails of said open back frame in allpermissible positions of tilting movement and vertical adjustment ofsaid back unit. i

3. A chair structure in accordance with claim 2, wherein the stop meansalso limits the tilting movement of the upper margin of said back unitso that it does not pass rearwardly of the front surface of the adjacenttop rail of the back frame in all permissible positions of tilting andvertical adjustment of said back unit.

4. A chair structure in accordance with claim 3, wherein the trunnionsand adjustable arms are mounted on the inner faces of the side rails ofsaid back frame and rearwardly of the lateral margins of said back unit.

5. In a chair having a seat and a substantially open back rest supportincluding stationary upright side rails, a pair of rearwardly projectingtrunnions mounted on said side rails substantially at the level of thesmall of the back of an average adult occupant, said trunnionshavinggenerally forwardly extending arms pivotally adjustable onhorizontal axes to varying fixed angular positions relative to saidtrunnions and forwardly thereof, a back unit pivotally mountedintermediate its top and bottom for relatively free tilting movement onthe ends of said arms to form the back rest of said chair, said backunit being vertically adjustable within said open back rest support byvarying the angular positions of said arms relative to said trunnions.

6. A chair structure in accordance with claim 5, wherein stop means areprovided for limiting the angular adjustment of said arms relative tosaid trunnions so as to maintain the front face of said back unit alongthe side margins thereof in front of the side rails of said back rest inall permissible positions of tilting movement and vertical adjustment ofsaid back unit relative to said back frame.

7. A chair structure in accordance with claim 6, wherein the stop meansare fixed on said trunnions and extend into position to be engaged bysaid arms at the limit of angular adjustment of the latter relative tosaid trunnions.

8. In a chair having a seat and a substantially open back frame definedby continuous top and side rails, a pair of rearwardly extendingtrunnions mounted on said side rails having armsv pivotally adjustableon horizontal axes to varying fixed angular positions relative to saidtrunnions, a back unit pivotally mounted intermediate its top and bottomand approximately at the level of the small of the back of an averageadult occupant for relatively free tilting movement on the ends of saidarms, said back unit being vertically adjustable within said open backframe by varying the angular positions of said arms relative tosaidtrunnions, said arms normally extending forwardly of their axes on saidtrunnions and being pivoted to the lateral margins of said back unitrearwardly of the latter.

9. A chair structure in accordance with claim 8,

v wherein stop means are provided for limiting the angular adjustment ofsaid arms relative to said trunnions so as to prevent the front face ofsaid back unit along the upper and side margins thereof, from passingrearwardly of the vtop and side rails, respectively, of said open backframe, in all permissible positions of tilting movement of said backunit relative to said arms.

10. In a chair having a seat and a back rest support includingstationary upright side rails, a

pair of rearwardly extending trunnions mounted on said side rails havingforwardly projecting arms pivotally adjustable on horizontal axesdisposed approximately at the level of the small of the back of anaverage adult occupant to vary the forward angle of said arms relativeto said trunnions, a back unit pivotally mounted for relatively freetilting movement on the ends; of said arms to form the back rest of saidchair between said upright side rails, and said back unit being bodilyadjustable vertically between said side rails by the angular adjustmentof said arms.

JOHN S. BURDICK.

REFERENCES CITED The following references are of record in the

